void main() {
  // Map 字典 - 类似JS中对象

  Map goods = {
    'id': 1,
    'name': '苹果',
    'price': 10.0,
  };

  print(goods['id']);  // 查询

  goods['price'] = 100.0;
  goods['num'] = 2;

  print(goods);

  goods.remove('num');
  print(goods);

  goods.forEach((key, value) {
    print('$key--$value');
  });

  goods.clear();
}
